1. Field of the Invention
This invention is related to lighting assemblies and is more particularly related to fluorescent lighting assemblies using electronic ballasts. More particularly, this invention is related to a fluorescent subassembly or lampholder including ballast components and integral fluorescent sockets.
2. Description of the Prior Art
Conventional ballasts used in overhead troffers or luminaires include lamps, ballasts and socket subassemblies or lampholders. The ballast or ballasts are mounted at the center of the troffer and attached to the top of the troffer. Wires extend from the ballast or ballasts to sockets located at opposite ends of the troffer. For a four lamp assembly, wires must be connected to sockets at both ends of the four lamps. When a defective ballast is replaced, often on a trial and error basis, these wires must be disconnected and reconnected. Installation and maintenance of conventional lighting assemblies is therefor time consuming and the manufacturing cost of the lighting assembly is increased.
One approach to simplifying and therefore reducing the cost of ballast installation is disclosed in U.S. Pat. No. 5,720,546 assigned to The Whitaker Corporation. This patent discloses an integral ballast that can be mounted at one end of a lighting assembly. A neutral wire is connected to the opposite end of the lighting assembly and this wiring must be completed during assembly of the lighting fixture. U.S. patent application Ser. No. 08/967,534 discloses a lighting assembly in which a ballast subassembly, including a ballast circuit similar to the MULTILITE MUL120 ballast circuit, can be mounted on a single end of a troffer with commoning contacts located at the opposite end. The ballast components are mounted on a printed circuit board positioned in a metal housing with conventional fluorescent sockets mounted on the exterior of the housing and connected to the printed circuit board.
U.S. Pat. No. 5,013,253 discloses another approach to simplifying the construction of fluorescent lighting fixtures. This patent discloses a method of wiring an otherwise conventional fluorescent lampholder in which wire leads are positioned in an insulating housing to connect terminals in integrally molded lamp sockets with an external connector block. Conventional external ballasts can then be wired to lamp sockets using this external connector block.